Commutation failure(CF)is a frequent dynamic event at inverter of LCC-HVDC systems caused by AC side faults which can lead to inverter blocking,interruption of active power transfer,and even system blackout.To elimina...Commutation failure(CF)is a frequent dynamic event at inverter of LCC-HVDC systems caused by AC side faults which can lead to inverter blocking,interruption of active power transfer,and even system blackout.To eliminate CFs and improve system performance,new Flexible LCC-HVDC topologies have been proposed in previous research but with limited analysis on its economic performance.Therefore,to further validate the applicability of Flexible LCC-HVDC topologies,this paper utilizes Life-Cycle Cost Analysis model to analyze the life-cycle cost of inverter stations for conventional LCCHVDC,Capacitor Commutated Converter based HVDC(CCCHVDC)topology and Flexible LCC-HVDC topologies including Controllable Capacitor based Flexible LCC-HVDC,AC Filterless Controllable Capacitor based Flexible LCC-HVDC and improved Flexible LCC-HVDC.Through a case study based on a 500 kV,1000 MW LCC-HVDC scheme,comparison results show that the AC Filterless Controllable Capacitor based Flexible LCCHVDC topology and the improved Flexible LCC-HVDC topology have lower cost than the conventional LCC-HVDC and CCCHVDC topologies,which proves that the elimination of CFs can be achieved with reduced cost.展开更多
为了进一步提升串联电压换相换流器(series voltage commutated converter,SVCC)的换相失败抑制能力和运行稳定性,该文提出一种适用于SVCC的新型换相失败抑制方法,根据交流电压跌落程度灵活控制接入系统的变流链电容电压值,通过配合阀...为了进一步提升串联电压换相换流器(series voltage commutated converter,SVCC)的换相失败抑制能力和运行稳定性,该文提出一种适用于SVCC的新型换相失败抑制方法,根据交流电压跌落程度灵活控制接入系统的变流链电容电压值,通过配合阀组换相过程来构造变流链子模块的提前触发脉冲信号,解决SVCC变流链子模块运行时电容电压不平衡的问题,提升直流输电系统换相失败抵御能力。此外,还提出适用于SVCC系统的故障检测方法,利用最小方差(least error squares,LES)滤波器快速提取电网基波电压信息,检测受端电网故障,并获得表征受端电网故障程度的变流链电容电压控制指令。同时从理论上分析SVCC变流链可在电容电压调整过程中为系统提供更多的无功功率,降低换流器对交流电网的无功需求。最后,在PSCAD/EMTDC环境下搭建模型进行验证,结果表明SVCC新型控制方法可以提升直流输电系统的换相失败抵御能力,并在受端电网故障下降低阀组对电网的无功需求。展开更多
基金supported by a collaborative project between the University of Birmingham and C-EPRI Electric Power Engineering Co.Ltd under grant“Key Technologies of Flexible LCC Converter with Controllable Capacitors”(SGNRPG00WZQT2100564A).
文摘Commutation failure(CF)is a frequent dynamic event at inverter of LCC-HVDC systems caused by AC side faults which can lead to inverter blocking,interruption of active power transfer,and even system blackout.To eliminate CFs and improve system performance,new Flexible LCC-HVDC topologies have been proposed in previous research but with limited analysis on its economic performance.Therefore,to further validate the applicability of Flexible LCC-HVDC topologies,this paper utilizes Life-Cycle Cost Analysis model to analyze the life-cycle cost of inverter stations for conventional LCCHVDC,Capacitor Commutated Converter based HVDC(CCCHVDC)topology and Flexible LCC-HVDC topologies including Controllable Capacitor based Flexible LCC-HVDC,AC Filterless Controllable Capacitor based Flexible LCC-HVDC and improved Flexible LCC-HVDC.Through a case study based on a 500 kV,1000 MW LCC-HVDC scheme,comparison results show that the AC Filterless Controllable Capacitor based Flexible LCCHVDC topology and the improved Flexible LCC-HVDC topology have lower cost than the conventional LCC-HVDC and CCCHVDC topologies,which proves that the elimination of CFs can be achieved with reduced cost.
